[LTC] Adopt more LazyGraphExecutor virtual interfaces (#4314)
Summary:
This patch tries to adopt even more LazyGraphExecutor virtual interfaces:
1. LazyGraphExecutor::Async.
2. TensorCollectionBarrier
3. SyncLiveTensorsGraph
And comments on methods that we don't adopt.
This depends on pytorch/pytorch#90650.
Test Plan:
CI.
